U.S. patent application number 11/380828 was filed with the patent office on 2006-11-02 for ink-jet recording apparatus.
This patent application is currently assigned to Brother Kogyo Kabushiki Kaisha. Invention is credited to Masahiko Sasa.
Application Number | 20060244803 11/380828 |
Document ID | / |
Family ID | 37234033 |
Filed Date | 2006-11-02 |
United States Patent
Application |
20060244803 |
Kind Code |
A1 |
Sasa; Masahiko |
November 2, 2006 |
Ink-Jet Recording Apparatus
Abstract
An ink-jet recording apparatus is provided which can perform
image recording on a recording medium being conveyed while
restraining a curl at the front end of the recording medium. The
ink-jet recording apparatus has an upstream curve forming portion
that curves a recording medium being conveyed into a nearly U-shape
when viewed in a cross selection orthogonal to a conveying
direction of the recording medium, and an upstream conveying
direction change portion that shifts the conveying direction of the
recording medium being conveyed from the feed tray to between a
platen and a recording head such that the recording medium is
curved to form a nearly U-shape when viewed in a cross section
along the conveying direction.
Inventors: |
Sasa; Masahiko; (Aichi-ken,
JP) |
Correspondence
Address: |
BAKER BOTTS LLP;C/O INTELLECTUAL PROPERTY DEPARTMENT
THE WARNER, SUITE 1300
1299 PENNSYLVANIA AVE, NW
WASHINGTON
DC
20004-2400
US
|
Assignee: |
Brother Kogyo Kabushiki
Kaisha
Nagoya-shi
JP
467-8561
|
Family ID: |
37234033 |
Appl. No.: |
11/380828 |
Filed: |
April 28, 2006 |
Current U.S.
Class: |
347/104 |
Current CPC
Class: |
B41J 13/103
20130101 |
Class at
Publication: |
347/104 |
International
Class: |
B41J 2/01 20060101
B41J002/01 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 28, 2005 |
JP |
2005132194 |
Claims
1. An ink-jet recording apparatus comprising:. a feed tray that can
mount a recording medium thereon, a conveying mechanism that
conveys the recording medium from the feed tray, a platen that
supports the recording medium conveyed by the conveying mechanism,
a recording head that selectively ejects ink from nozzles of the
recording head onto the recording medium on the platen while moving
orthogonally to a conveying direction of the recording medium by
the conveying mechanism to perform image recording on the recording
medium, an upstream curve forming portion which curves the
recording medium conveyed by the conveying mechanism into a nearly
U-shape when viewed in a cross section orthogonal to the conveying
direction, and an upstream conveying direction change portion which
shifts the conveying direction of the recording medium conveyed
from the feed tray to between the platen and the recording head by
the conveying mechanism such that the recording medium is curved to
form a U-shape when viewed in a cross section along the conveying
direction.
2. The ink-jet recording apparatus according to claim 1, wherein
the upstream curve forming portion is formed such that a degree, at
which the recording medium conveyed by the conveying mechanism is
curved to form a nearly U-shape cross section orthogonal to the
conveying direction of the recording medium, is smaller as a
distance to the upstream conveying direction change portion is
closer.
3. The ink-jet recording apparatus according to claim 1, wherein
the upstream conveying direction change portion shifts the
conveying direction of the recording sheet such that an angle
.theta..sub.1 (.degree.), formed by a conveying direction of the
recording medium conveyed from the feed tray by the conveying
mechanism and a conveying direction of the recording medium
conveyed between the platen and the recording head, satisfies the
following relational expression (i), 0<.theta..sub.1.ltoreq.70
(i).
4. The ink-jet recording apparatus according to claim 1, further
comprising a biasing unit that biases a part of the recording sheet
conveyed by the conveying mechanism, which has passed between the
platen and the recording head, to a direction opposite to the
conveying direction of the recording medium.
5. The ink-jet recording apparatus according to claim 1, wherein
the upstream curve forming portion and the upstream conveying
direction change portion are provided in the feed tray.
6. The ink-jet recording apparatus according to claim 1, further
comprising: a downstream conveying direction change portion that
shifts the conveying direction of the recording medium on which
image recording has been performed by the recording head such that
the recording medium is curved to form a U-shape when viewed in a
cross section along the conveying direction, and a downstream curve
forming portion that curves the recording medium of which conveying
direction is shifted by the downstream conveying direction change
portion after image recording has been performed by the recording
head thereon, into a nearly U-shape when viewed in a cross section
orthogonal to the conveying direction.
7. The ink-jet recording apparatus according to claim 5, wherein
the downstream curve forming portion is formed such that a degree,
at which the recording medium conveyed by the conveying mechanism
is curved to form a nearly U-shape cross section orthogonal to the
conveying direction of the recording medium, is larger as a
distance from the downstream conveying direction change portion is
increased.
8. The ink-jet recording apparatus according to claim 5, wherein
the downstream conveying direction change portion shifts the
conveying direction of the recording medium such that an angle
.theta..sub.2 (.degree.), formed by a conveying direction of the
recording medium on which image recording has been performed by the
recording head and a conveying direction of the recording medium
conveyed toward the downstream curve forming portion, satisfies the
following relational expression (ii), 0<.theta..sub.2.ltoreq.70
(ii).
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of Japanese Patent
Application No. 2005-132194 filed Apr. 28, 2005 in the Japan Patent
Office, the disclosure of which is incorporated herein by
reference.
BACKGROUND
[0002] This invention relates to an ink-jet recording apparatus
that performs image recording on a conveyed recording medium while
controlling an upward curl at the front end of the recording
medium.
[0003] Conventional ink-jet recording apparatus are known to
perform image recording on a recording medium being conveyed on a
platen by selectively ejecting ink from the nozzles of a recording
head onto the recording medium while moving the recording head
orthogonally to the conveying direction of the recording
medium.
[0004] In this case, if there is a curl on a recording medium on
which such ink-jet recording apparatus perform image recording, the
recording medium is lifted during conveyance on the platen and this
shortens the distance to the recording head. Thus, image recording
is not performed in an orderly fashion. For example, in case of a
large curl, the recording head may be brought into contact with the
recording medium. Ink adhered to the nozzle face of the recording
head may be transferred to the recording medium, thereby leading to
a degradation of the image quality. Or, the recording medium may
collide with the recording head and get jammed. In case of a small
curl, ink from the recording head may not be ejected onto the
targeted positions and the recorded image may be distorted. Also,
white lines and dark-colored lines may appear in the recorded image
and deteriorate the image quality.
[0005] Among the aforementioned ink-jet recording apparatus, there
is an apparatus that guides a recording medium to between the
platen and the recording head while suppressing the recording
medium by two pinch rollers and a carriage guide, respectively
provided upstream of the recording head, to prevent the recording
medium from being lifted. Such an ink-jet recording apparatus
curves the recording medium along a direction orthogonal to the
conveying direction of the recording medium to correct the curl of
the recording medium. Accordingly, the recording medium is evenly
held on the platen and is not lifted.
SUMMARY
[0006] However, even in the aforementioned ink-jet recording
apparatus, a conveyed recording medium is lifted from the platen,
shortening the distance to the recording head, if there is an
upward curl at the front end of the recording medium. Thus, there
is a problem that a desired image is not recorded In other words, a
downward curl at the front end of a recording medium, for example,
can be corrected by abutting the front end of the recording medium
against the platen, guided by the two pinch rollers and the
carriage guide. The recording medium is evenly held on the platen
and is not lifted. On the other hand, an upward curl at the front
end of a recording medium remains as it is even if the recording
medium is guided by the two pinch rollers and the carriage guide.
The recording medium conveyed on the platen is lifted and this
shortens the distance to the recording head. As a result, image,
recording is not successfully performed.
[0007] The present invention is made to solve the above problems.
It would be desirable to provide an ink-jet recording apparatus
that can perform image recording on a conveyed recording medium,
while restraining a curl at the front end of the recording
medium.
[0008] It is desirable that an ink-jet recording apparatus of the
present invention includes: a feed tray that can mount a recording
medium thereon; a conveying mechanism that conveys the recording
medium from the feed tray; a platen that supports the recording
medium conveyed by the conveying mechanism; a recording head that
selectively ejects ink from nozzles onto the recording medium on
the platen, while moving orthogonally to the direction of
conveyance of the recording medium by the conveying mechanism to
perform image recording on the recording medium; an upstream curve
forming portion which curves the recording medium, conveyed by the
conveying mechanism, into a nearly U-shape when viewed in a cross
section orthogonal to the conveying direction; and an upstream
conveying direction change portion which shifts the conveying
direction of the recording medium, conveyed from the feed tray to
between the platen and the recording head by the conveying
mechanism, such that the recording medium is curved to form a
nearly U-shape when viewed in a cross section along the conveying
direction.
[0009] According to the ink-jet recording apparatus of the present
invention, the recording medium being conveyed is curved to form a
nearly U-shape when viewed in a cross section orthogonal to the
conveying direction of the recording medium. Then, the conveying
direction is shifted such that the recording medium is curved to
form a nearly U-shape when viewed in a cross section along the
conveying direction, so that the front end of the recording medium
is pressed against the platen. More particularly, if a recording
medium, conveyed from the feed tray to between the platen and the
recording head by the conveying mechanism, is curled into a nearly
U-shape when viewed in a cross section orthogonal to the conveying
direction of the recording medium, the recording medium comes into
a state curled along the conveying direction of the recording
medium. This makes it difficult for the recording medium to be
curled orthogonal to the conveying direction. Subsequently, the
upstream conveying direction change portion shifts the conveying
direction of the recording medium such that the recording medium is
curved to form a nearly U-shape when viewed in a cross section
along the conveying direction. As a result, the front end of the
conveyed recording medium is pressed against the platen. Even if
the recording medium is curled along a direction orthogonal to the
conveying direction, the part of the recording medium located on
the platen is flattened. Accordingly, regardless of an upward curl
at the front end of the recording medium being conveyed, image
recording can be performed with the curl being controlled.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The invention will now be described below, by way of
example, with reference to the accompanying drawings, in which:
[0011] FIG. 1 is a perspective view of an ink-jet recording
apparatus;
[0012] FIG. 2 is a plan view of the ink-jet recording
apparatus;
[0013] FIG. 3 is a cross sectional view taken by a line III-III in
FIG. 2;
[0014] FIG. 4 is an explanatory view showing a schematic structure
of a discharge tray taken from a direction IV;
[0015] FIG. 5 is a cross sectional view taken by a line V-V in FIG.
3;
[0016] FIG. 6 is an explanatory view showing a schematic structure
of a feed tray taken from a direction VI;
[0017] FIG. 7 is a cross sectional view taken by a line VII-VII in
FIG. 3;
[0018] FIG. 8 is an explanatory view showing a state in which a
recording sheet is curved to form a nearly U-shape when viewed in a
cross section orthogonal to a conveying direction of the recording
medium, and the conveying direction is shifted such that the
recording medium is curved to form a nearly U-shape when viewed in
a cross section along the conveying direction;
[0019] FIG. 9 is an explanatory view showing the recording sheet
being conveyed; and
[0020] FIG. 10A is an explanatory view showing a schematic
structure of the feed tray taken from a direction IXA in FIG. 9,
FIG. 10B is an explanatory view showing a schematic structure of
the discharge tray taken from a direction IXB, FIG. 10C is an
explanatory view showing a schematic structure of a delivery roller
and a holding roller taken by a line IXC-IXC, and FIG. 10D is an
explanatory view showing a schematic structure of a discharge
roller and spur rollers taken by a line IXD-IXD.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] Hereinafter in an ink-jet recording apparatus 1, the side
where there is a discharge tray is referred to as the "front side",
and the side where there is a feed tray is referred to as the "rear
side", as shown in FIG. 1. Likewise, the side where a recording
head is located with respect to a platen is referred to as the
"upper side", and the side where the platen is located with respect
to the recording head is referred to as the "lower side".
Furthermore, the "right side" and the "left side" are indicated as
the right and left sides of the ink-jet recording apparatus 1 when
viewed from the "front side" toward the "rear side".
[0022] [description of Ink-Jet Recording Apparatus 1]
[0023] Referring to FIGS. 1 and 2, the ink-jet recording apparatus
1 performs image recording onto a recording sheet 12 by selectively
ejecting ink from nozzles of a recording head 51 mounted on a
recording unit 50 onto the recording sheet 12 conveyed on a platen
35, while moving the recording unit 50 orthogonally to a conveying
direction of the recording sheet 12.
[0024] [Description of Sheet Cassette 14]
[0025] As shown in FIG. 3, a sheet cassette 14, which can store a
plurality of recording sheets 12, is provided at the rear part of
the ink-jet recording apparatus 1. A feed roller 16 is provided at
the lower front portion of the feed cassette 14 where the feed
roller 16 is brought into contact with the topmost recording sheet
12. The feed roller 16 has a rotational axis along the width
direction of the recording sheet 12. The feed roller 16 can be
rotated by a driving force of a drive motor 101 (see FIG. 1) via a
gear group 102 and a shaft 103.
[0026] A feed tray 18, which mounts a recording sheet 12 thereon,
is provided inside the feed cassette 14. The feed tray 18 is curved
into a nearly U-shape (see FIG. 6) when viewed in a cross section
orthogonal to the conveying direction of the recording sheet 12.
The feed tray 18 is formed such that the degree of curvature is
smaller toward an upstream guide 21. As a result, a recording sheet
12 placed on the feed tray 18 curves into a nearly U-shape when
viewed in a cross section orthogonal to the conveying direction,
and the degree of curvature of the recording sheet 12 becomes
gradually smaller as the recording sheet 12 is conveyed. The feed
tray 18 is biased toward the feed roller 16 by a not shown coil
spring. That is, the recording sheet 12 on the feed tray 18 is
brought into contact with the feed roller 16 by the biasing force
of the coil spring, and conveyed on the upstream guide 21 by the
feed roller 16, which is driven and rotated by the drive motor
101.
[0027] [Description of Upstream Guide 21]
[0028] The upstream guide 21 is oriented such that an angle
.theta..sub.1 (.degree.), formed by a conveying surface 21a of the
upstream guide 21 and a conveying surface 35a of a later-explained
platen 35, is approximately 45.degree..
[0029] According to the inventor's experiments, a large driving
force is not required to convey a recording paper 12, a curl does
not remain on the recording paper 12, and a smooth change in the
conveying direction of the recording paper 12 is achieved, if the
angle .theta..sub.1 is set to satisfy the following relational
expression (i). 0<.theta..sub.1.ltoreq.70 (i)
[0030] The upstream guide 21 is also provided with support rollers
21b, 21b on both sides for supporting both right and left sides of
a recording sheet 12 (see FIG. 7).
[0031] [Description of Delivery Roller 31 and Holding Roller
32]
[0032] A feed/convey unit is provided at the front and obliquely
downward of the feed roller 16 inside of a cover frame 24. The
feed/convey unit includes a delivery roller 31 and a holding roller
32. The delivery roller 31 is driven and rotated by a motor. The
holding roller 32 has a rotational axis parallel to a rotational
axis of the delivery roller 31. The delivery roller 31 can be
rotated by the driving force of a stepping motor 111 via a not
shown gear group. The holding roller 32 is rotatably attached to a
roller holder 33. The roller holder 33 is rotatably supported by an
attachment shaft (not shown), and biased toward the delivery roller
31 by a not shown spring. That is, due to the biasing force of the
spring, the surface of the holding roller 32 is pressed against the
surface of the delivery roller 31. Thereby, a recording sheet 12
conveyed on the upstream guide 21 by the feed roller 16 is held
between the delivery roller 31 and the holding roller 32 and
delivered onto the conveying surface 35a of the platen 35.
[0033] The delivery roller 31 has supports 31a, 31a (see FIG. 10C)
whose diameter is set larger than the diameter of the axial portion
of the delivery roller 31. The supports 31a, 31a can support both
left and right sides of a conveyed recording sheet 12.
[0034] [Description of Platen 35]
[0035] The aforementioned platen 35 is designed to support a
recording sheet 12, conveyed by the delivery roller 31 and the
holding roller 32, with the conveying surface 35a. A plurality of
not shown ribs are formed on the conveying surface 35a of this
platen 35 to extend in the conveying direction of the recording
sheet 12.
[0036] An upstream end portion 35b of the platen 35 is formed such
that the recording sheet 12 is curved to form a nearly U-shape when
viewed in a cross section along the conveying direction of a
recording sheet 12. That is, as is the case with the conveying
surface 21a of the upstream guide 21, the angle .theta..sub.1
(.degree.), formed by the upstream end portion 35b and the
conveying surface 35a, is approximately 45.degree.. According to
the inventor's experiments, if the angle .theta..sub.1 is set to
satisfy the above relational expression (i), the same effect as
above can be achieved. The conveying direction of a recording sheet
12, conveyed from the feed tray 18 to between the platen 35 and the
recording head 51 by the feed/convey unit, is shifted by the
upstream end portion 35b of the platen 35 such that the recording
sheet 12 is curved to form a nearly U-shape when viewed in a cross
section along the conveying direction.
[0037] A downstream end portion 35c of the platen 35 is formed such
that a recording sheet 12 is curved to form a nearly U-shape when
viewed in a cross section along the conveying direction. That is,
the downstream end portion 35c of the platen 35 is formed such that
an angle .theta..sub.2 (.degree.), formed by the downstream end
portion 35c and the conveying surface 35a, is approximately
45.degree..
[0038] According to the inventor's experiments, a large driving
force is not required to convey a recording paper 12, a curl does
not remain on the recording paper 12, and a smooth change in the
conveying direction of the recording paper 12 is achieved if the
angle .theta..sub.2 is set to satisfy the following relational
expression (ii). 0<.theta..sub.2.ltoreq.70 (ii)
[0039] As a result, the conveying direction of a recording sheet
12, discharged to a catch cassette 70 by the conveying mechanism,
is shifted by the downstream end portion 35c of the platen 35 such
that the recording sheet 12 is curved to form a nearly U-shape when
viewed in a cross section along the conveying direction.
[0040] [Description of Recording Unit 50]
[0041] The recording unit 50 is provided inside the cover frame 24.
The recording unit 50 includes the recording head 51 having a
recording face opposed to the top surface of the platen 35.
[0042] A plurality of ink chambers, each with a piezoelectric
element, are provided inside the recording head 51. Application of
voltage to the piezoelectric element changes the volume in the ink
chambers. The recording is performed by ejection of ink from
nozzles formed in the ink chambers onto the upper surface of the
recording sheet 12 on the conveying surface 35a of the platen
35.
[0043] The recording head 51 is mounted on a carriage 52. The
carriage 52 is attached to guide bars 53, 54 provided in a width
direction inside of the ink-jet recording apparatus 1. One end of
the carriage 52 is fixed to an endless belt 122, which connects a
drive pulley (not shown) and a driven pulley 123. The drive pulley
is driven by a carriage drive motor 121. The carriage 52
reciprocates along the guide bars 53, 54 via the endless belt 122
by the carriage drive motor 121 (see FIG. 1), while the recording
head 51 performs recording onto a recording sheet 12 in a width
direction of the recording sheet 12.
[0044] [Description of Discharge Roller 60 and Spur Rollers 61]
[0045] A discharge/convey unit, including a discharge roller 60 and
spur rollers 61, is provided downstream of the recording head 51.
The discharge roller 60 is driven and rotated by a motor. A
recording sheet 12, on which image recording has been performed, is
held between the discharge roller 60 and the spur rollers 61 to be
discharged. The discharge roller 60 can be rotated via a not shown
gear group by the driving force of the aforementioned stepping
motor 111. The discharge roller 60 is also provided with supports
60a, 60a whose diameter is set larger than the diameter of the
axial portion of the discharge roller 60. The supports 60a, 60a can
support both right and left ends of a conveyed recording sheet 12
(see FIG. 10D).
[0046] Each spur roller 61 is made of a thin plate material with a
plurality of sharp-pointed protrusions around the outer periphery.
That is, the ink is not dried on the upper surface of a recording
sheet 12 on which image recording has been performed. Therefore,
the use of a rubber roller having a large contact area is not
appropriate, unlike in other non-ink-jet printers. Instead, the
spur rollers 61 are used having a small contact area. Also, the
spur rollers 61 are rotatably attached to a plate-like spur roller
holder 62. The spur roller holder 62 is rotatably supported by an
attachment shaft 63 and is biased toward the discharge roller 60 by
a not shown spring. That is, the surface of each spur roller 61 is
pressed against the surface of the discharge roller 60 by the
biasing force of the spring. Thereby, a recording sheet 12, on
which image recording has been performed by the recording head 51
on the platen 35, is held between the discharge roller 60 and the
spur rollers 61 and is discharged onto a downstream guide 65.
[0047] [Delivery Amount of Delivery Roller 31 and Discharge Roller
60]
[0048] As noted above, the delivery roller 31 and the discharge
roller 60 are respectively rotationally driven by the stepping
motor 111 and the gear group. The delivery amount of the discharge
roller 60 is set to be slightly smaller than the delivery amount of
the delivery roller 31 by means of a friction clutch provided in a
drive transmission which drives the discharge roller 60. As a
result, when a recording sheet 12 is conveyed downstream by the
delivery roller 31 and the discharge roller 60, the recording sheet
12 is resisted by the slipping of the discharge roller 60 and the
spur rollers 61 and can be conveyed in a flattened state.
[0049] [Description of Downstream Guide 65]
[0050] The downstream guide 65 is formed such that the angle
.theta..sub.2 (.degree.), formed by the conveying surface 65a and
the conveying surface 35a of the platen 35, is approximately
45.degree., as is the case with the downstream end portion 35c of
the platen 35. According to the inventor's experiments, if the
angle .theta..sub.2 is set to satisfy the aforementioned relational
expression (ii), a large driving force is not required to convey a
recording paper 12, a curl does not remain on the recording paper
12, and a smooth change in the conveying direction of the recording
paper 12 is achieved.
[0051] [Description of Catch Cassette 70]
[0052] The catch cassette 70, which can store a plurality of
recording sheets 12 on which image recording has been performed, is
provided at the front of the ink-jet recording apparatus 1. A catch
roller 72 and spur rollers 74 are provided at the rear of the catch
cassette 70 and at the portion in contact with a topmost recording
sheet 12. The catch roller 72 has a rotational axis along a width
direction of the recording sheet 12. The recording sheet 12 is held
between the catch roller 72 and the spur rollers 74 to be
discharged. The catch roller 72 can be rotated via the gear group
104 by the driving force of the aforementioned drive motor 101 (see
FIG. 1). The catch roller 72 is also provided with supports 72a,
72a whose diameter is set larger than the diameter of the axial
portion of the catch roller 72. The supports 72a, 72a can support
both right and left ends of a conveyed recording sheet 12 (see FIG.
5).
[0053] A catch tray 76, for receiving a recording sheet 12 on which
image recording has been performed by the recording head 51, is
provided inside of the catch cassette 72. The catch tray 76 is
curved into a nearly U-shape when viewed in a cross section
orthogonal to the conveying direction of the recording sheet 12
(see FIG. 4). The degree of curvature of the catch tray 76 is
formed to be larger as the distance from the downstream guide 65 is
increased. As a result, a recording sheet 12 placed on the catch
tray 76 is curved to form a nearly U-shape when viewed in a cross
section orthogonal to the conveying direction. The degree of
curvature becomes gradually larger as the recording sheet 12 is
conveyed.
[0054] [Description of Maintenance Mechanism 80]
[0055] The ink-jet recording apparatus 1 is provided with a
maintenance mechanism 80 that does maintenance of the recording
head 51. The maintenance mechanism 80 includes a wiper (not shown),
a cap (not shown), and a drive motor (not shown). The wiper wipes a
head face of the recording head 51. The cap can seal a nozzle group
of the recording head 51. The drive motor respectively drives the
wiper and the cap.
[0056] Other components of the ink-jet recording apparatus 1 are
based on well known art. Therefore, a detailed explanation of the
other components is not provided.
[0057] [Description of Recording Operation of Ink-Jet Recording
Apparatus 1]
[0058] Now, the recording operation of the ink-jet recording
apparatus 1 is described referring to FIG. 9. FIG. 9 is an
explanatory view showing a recording sheet 12 being conveyed.
[0059] A recording sheet 12, stored in the sheet cassette 14, is
curved to form a nearly U-shape, when viewed in a cross section
orthogonal to the conveying direction. The recording sheet 12 is in
a state deformed by the feed tray 18 (see FIG. 10A) such that the
degree of curvature becomes gradually smaller as the recording
sheet 12 is conveyed. The recording sheet 12, deformed by the feed
tray 18, is delivered to the delivery roller 31 on and along the
upstream guide 21 by the feed roller 16 rotating counterclockwise.
The recording sheet 12, conveyed on the upstream guide 21, is
brought into a state in which both right and left ends of the
recording sheet 12 are lifted by the support rollers 21b, 21b (see
FIG. 7).
[0060] Subsequently, the recording sheet 12, delivered on and along
the upstream guide 21, is held between the delivery roller 31
rotating clockwise and the holding roller 32 rotating
counterclockwise, and delivered onto the conveying surface 35a of
the platen 35. In this case, the conveying direction of the part of
the recording sheet 12, located on the upstream end portion 35b of
the platen 35, is shifted by the upstream end portion 35a of the
platen such that the part is curved to form a nearly U-shape when
viewed in a cross section along the conveying direction. As a
result, the front end of the recording sheet 12 is pressed against
the conveying surface 35a of the platen 35, and the part of the
recording sheet 12 located on the conveying surface 35a of the
platen 35 is flattened, even if the recording sheet 12 was curled
along a direction orthogonal to the conveying direction (see FIG.
8). Also, the recording sheet 12 is brought into a state in which
both the right and left ends thereof are lifted by the supports
31a, 31a (see FIG. 10C).
[0061] When the recording sheet 12 reaches the conveying surface
35a, rotation of the delivery roller 31 is suspended, and the
recording head 51 is driven. While moving along the travel
direction of the carriage 52, the recording head 51 ejects ink onto
the upper surface of the recording sheet 12 for recording. When the
recording head 51 completes recording for one line, the delivery
roller 31 again rotates and delivers the recording sheet 12 to the
next recording position, and the same operation as above is
performed.
[0062] After repeated recording and delivery, the recording sheet
12 is held between the discharge roller 60 and the spur rollers 61
and discharged onto the catch tray 76 of the catch cassette 70. In
this case, the conveying direction of the part of the recording
sheet 12, located on the downstream end portion 35c of the platen
35, is shifted by the downstream end portion 35 of the platen 35
such that the part is curved to form a nearly U-shape when viewed
in a cross section along the conveying direction. Also, the
recording sheet 12 is brought into a state in which both the right
and left ends thereof are lifted by the supports 60a, 60a of the
discharge roller 60 (see FIG. 10D). Moreover, the recording sheet
12 is deformed by the catch tray 76 such that the recording sheet
12 is curved to form a nearly U-shape when viewed in a cross
section orthogonal to the conveying direction and that the degree
of curvature becomes gradually larger as the recording sheet 12 is
conveyed (see FIG. 10B). As a result, the part of the recording
sheet 12 located on the conveying surface 35a of the platen 35 is
pressed against the platen 35 and flattened. The recording sheet
12, received in the catch tray 76, is brought into a state in which
both the right and left ends thereof are lifted by the supports
72a, 72a of the catch roller 72 (see FIG. 5).
[0063] [Effects]
[0064] (1) According to the ink-jet recording apparatus 1 of the
present embodiment, a recording sheet 12 stored in the sheet
cassette 14 is curved to form a nearly U-shape when viewed in a
cross section orthogonal to the conveying direction. The recording
sheet, when being conveyed, is deformed by the feed tray 18 such
that the degree of curvature becomes gradually smaller.
Furthermore, the conveying direction of the recording sheet 12,
delivered onto the conveying surface 35a of the platen 35 by the
delivery roller 31, and the holding roller 32, is shifted by the
upstream end portion 35b of the platen 35 such that the recording
sheet 12 is curved to form a nearly U-shape when viewed in a cross
section along the conveying direction. Therefore, the front end of
the recording sheet 12 is pressed against the conveying surface 35a
of the platen 35. Even if the recording sheet 12 was curled along a
direction orthogonal to the conveying direction, the part of the
recording sheet 12 located on the conveying surface 35a of the
platen 35 is flattened (see FIG. 8). Accordingly, the ink-jet
recording apparatus 1 of the present embodiment can perform
recording while controlling the curl of the recording sheet 12.
[0065] (2) According to the ink-jet recording apparatus 1 of the
present embodiment, the feed tray 18 is curved into a nearly
U-shape when viewed in a cross section orthogonal to the conveying
direction of a recording sheet 12. The degree of curvature is
smaller toward the upstream guide 21. Such a constitution enables
the upstream guide 21 to smoothly shift the conveying direction of
the recording sheet 12.
[0066] (3) According to the ink-jet recording apparatus 1 of the
present embodiment, the support rollers 21b, 21b of the upstream
guide 21 lift both right and left ends of a recording sheet 12
conveyed on the upstream guide 21. Furthermore, the supports 31a,
31a of the delivery roller 31 lift both the right and left ends of
the recording sheet 12. Therefore, it is possible for the upstream
guide 21 to smoothly shift the conveying direction of the recording
sheet 12.
[0067] (4) According to the ink-jet recording apparatus 1 of the
present embodiment, the upstream guide 21 is formed such that the
angle .theta..sub.1 (.degree.), formed by the conveying surface 21a
of the upstream guide 21 and the conveying surface 35a of the
platen 35, is approximately 45.degree.. Therefore, a large driving
force is not required to convey a recording paper 12, a curl does
not remain on the recording paper 12, and a smooth change in the
conveying direction of the recording paper 12 is achieved.
According to the inventor's experiments, if the angle .theta..sub.1
is set to satisfy the aforementioned relational expression (i), the
same effects as above can be achieved.
[0068] (5) According to the ink-jet recording apparatus 1 of the
present embodiment, the sheet feeding amount of the delivery roller
31 is set to be slightly larger than the sheet feeding amount of
the discharge roller 60. Therefore, a recording sheet 12, when
being conveyed downward by both the delivery roller 31 and the
discharge roller 60, is resisted by the slipping of the discharge
roller 60 and the spur rollers 61 so that the recording sheet 12
can be conveyed in a flattened state. That is, no tensile force
operates on the recording sheet 12. There is no concern that a part
of the recording sheet 12, located on the conveying surface 35a of
the platen 35, is lifted.
[0069] (6) According to the ink-jet recording apparatus 1 of the
present embodiment, the conveying direction of a recording sheet
12, discharged by the discharge roller 60 and the spur rollers 61,
is shifted by the downstream end portion 35c of the platen 35 such
that the recording sheet 12 is curved to form a U-shape when viewed
in a cross section along the conveying direction. Moreover, the
recording sheet 12 is curved to form a U-shape when viewed in a
cross section orthogonal to the conveying direction. The recording
sheet 12, when being conveyed, is brought into a deformed state by
the discharge tray 76 such that the degree of curvature becomes
gradually larger (see FIG. 10B). As a result, the part of the
recording sheet 12 located on the conveying surface 35a of the
platen 35 is pressed against the platen 35 and flattened.
Therefore, even if a part of the recording sheet 12 which has
passed the upstream guide 21 is larger than the other part,
recording can be performed onto the recording sheet 12 while the
curl of the recording sheet 12 is still under control.
[0070] (7) According to the ink-jet recording apparatus 1 of the
present embodiment, the discharge tray 76 is curved into a nearly
U-shape when viewed in a cross section orthogonal to the conveying
direction of a recording sheet 12. The degree of curvature is
formed to be larger as the distance from the downstream guide 65 is
increased. Such a constitution enables the downstream guide 65 to
smoothly shift the conveying direction of the recording sheet
12.
[0071] (8) According to the ink-jet recording apparatus 1 of the
present embodiment, the supports 60b, 60b of the discharge roller
60 lift both right and left ends of a recording sheet 12 being
conveyed. Furthermore, the supports 72a, 72a of the discharge
roller 72 lift both the right and left ends of the recording sheet
12. Therefore, it is possible for the downstream guide 65 to
smoothly shift the conveying direction of the recording sheet
12.
[0072] (9) According to the ink-jet recording apparatus 1 of the
present embodiment, the downstream guide 65 is formed such that the
angle .theta..sub.2 (.degree.), formed by the conveying surface 65a
of the downstream guide 65 and the conveying surface 35a of the
platen 35, is approximately 45.degree.. Therefore, a large driving
force is not required to convey a recording paper 12, a curl does
not remain on the recording paper 12, and a smooth change in the
conveying direction of the recording paper 12 is achieved.
According to the inventor's experiments, if the angle .theta..sub.2
is set to satisfy the aforementioned relational expression (ii),
the same effects as above can be achieved.
[0073] An embodiment of the present invention is described in the
above. However, the present invention can be practiced in various
manners without departing from the technical scope of the
invention.
[0074] In the above embodiment, the sheet feeding amount of the
discharge roller 60 is set to be slightly smaller than the sheet
feeding amount of the delivery roller 31 by means of a friction
clutch provided in the drive transmission which drives the
discharge roller 60. However, a recording sheet 12 can be delivered
in a flattened state by slipping the discharge roller 60 and a
recording sheet 12 by friction. Even with this constitution, no
tensile force operates on the recording sheet 12. There is no
concern that the part of the recording sheet 12 located on the
conveying surface 35a of the platen 35 is raised.
* * * * *